Cosmetic and pharmaceutical preparations comprising ascorbic acid derivatives

ABSTRACT

Use of ascorbic acid derivatives of the formula I  
                 
 
     where the variables independently of one another have the following meanings:  
     R 1  is hydrogen, C 1 -C 20 -acyl, C 1 -C 12 -alkoxycarbonyl, C 1 -C 12 -alkyl,  
     R 2  is hydrogen, C 1 -C 20 -acyl, C 1 -C 12 -alkoxycarbonyl, C 1 -C 12 -alkyl,  
     where R 1  and R 2 , together with the oxygen atoms to which they are bonded and the carbon atoms bonded to the oxygen atoms, can form an unsubstituted or substituted heterocycle,  
     R 3  is hydrogen or a cation selected from the group consisting of NH 4   + , alkali metal and alkaline earth metal cations,  
     R 4  is C 1 -C 12 -alkoxycarbonyl,  
     for cosmetic and pharmaceutical preparations is described.

[0001] Ascorbic acid (vitamin C) is an antioxidant which is widely employed in cosmetics. Together with vitamin E it counteracts the oxidation of unsaturated fatty acids and thus also prevents lipoperoxide formation (O. Isler, G. Brubacher, S. Ghisla, B. Krautler eds.; Vitamine II (vitamins II), G. Thieme Verlag, Stuttgart, N. Y., 431, 1988). As a vitamin, ascorbic acid is also involved in the metabolism, for instance in the hydroxylation of proline in collagen synthesis (J. J. Burns, J. M. Rivers, L. J. Machin eds.; Third Conference on vitamin C, Ann. N.Y. Acad. Sci., 498 (1987) 1-533).

[0002] On account of the excessively low stability of ascorbic acid in cosmetic formulations, it is often necessary to employ stabilized derivatives of ascorbic acid. Examples of these are sodium L-ascorbate monophosphate (JP 07082127, JP 05331020), L-ascorbic acid 2-O-D-glucoside (T. Sakamoto et al.; 19th IFSCC Congress, Sydney, 1996, Vol. 2, Paper No. 14) and 5,6-isopropylidene-L-ascorbic acid 2-phosphate (JP 08269074).

[0003] The abovementioned stabilized ascorbic acid derivatives, however, frequently have the disadvantage that they are too poorly soluble in cosmetic or pharmaceutical oils.

[0004] It is therefore an object of the invention to make available stable ascorbic acid derivatives, which do not have the abovementioned disadvantages, for cosmetic and pharmaceutical preparations.

[0005] We have found that this object is achieved according to the invention by use of ascorbic acid derivatives of the formula I,

[0006] where the variables independently of one another have the following meanings:

[0007] R¹ is hydrogen, C₁-C₂₀-acyl, C₁-C₁₂-alkoxycarbonyl, C₁-C₁₂-alkyl;

[0008] R² is hydrogen, C₁-C₂₀-acyl, C₁-C₁₂-alkoxycarbonyl, C₁-C₁₂-alkyl,

[0009] where R¹ and R², together with the oxygen atoms to which they are bonded and the carbon atoms bonded to the oxygen atoms, can form an unsubstituted or substituted heterocycle;

[0010] R³ is hydrogen or a cation selected from the group consisting of NH₄ ⁺, alkali metal and alkaline earth metal cations;

[0011] R⁴ is C₁-C₁₂-alkoxycarbonyl,

[0012] for cosmetic and pharmaceutical preparations.

[0013] Preferred compounds of formula I are those where the variables have the following meanings:

[0014] R¹ is hydrogen, C₁-C₂₀-acyl, C₁-C₁₂-alkoxycarbonyl, C₁-C₁₂-alkyl;

[0015] R² is hydrogen, C₁-C₂₀-acyl, C₁-C₁₂-alkoxycarbonyl, C₁-C₁₂-alkyl,

[0016] where R¹ and R², together with the oxygen atoms to which they are bonded and the carbon atoms bonded to the oxygen atoms, can form an unsubstituted or substituted heterocycle and

[0017] R¹ must not be a C₁-C₁₂-alkoxycarbonyl radical if R² is hydrogen;

[0018] R³ is hydrogen or a cation selected from the group consisting of NH₄ ⁺, alkali metal and alkaline earth metal cations;

[0019] R⁴ is C₁-C₁₂-alkoxycarbonyl.

[0020] Very particularly preferred compounds of the formula I are those where the variables have the following meanings:

[0021] R¹ is hydrogen, C₁-C₂₀-acyl, C₁-C₆-alkoxycarbonyl;

[0022] R² is hydrogen, C₁-C₂₀-acyl, C₁-C₆-alkoxycarbonyl,

[0023] where R¹ must not be a C₁-C₆-alkoxycarbonyl radical if R² is hydrogen;

[0024] R³ is hydrogen or a cation selected from the group consisting of NH₄ ⁺, alkali metal and alkaline earth metal cations;

[0025] R⁴ is C₁-C₆-alkoxycarbonyl.

[0026] In the ascorbic acid derivatives of the formula I according to the invention, acyl radicals for R¹ and R² are to be understood as meaning branched or unbranched, saturated or unsaturated, if appropriate polyunsaturated, C₁-C₂₀-acyl chains.

[0027] Examples of these are acyl radicals of formic, acetic, propionic, n-butyric, isobutyric, sorbic, n-valeric, isovaleric, caproic, caprylic, capric, undecanoic, lauric, tridecanoic, myristic, pentadecanoic, palmitic, palmitoleic, stearic, oleic, linoleic, linolenic, nonadecanoic and arachidonic acid.

[0028] Preferred acyl radicals are those of long-chain fatty acids having C₁₀ to C₂₀ carbon chains, in particular acyl radicals of lauric, palmitic, palmitoleic, stearic, oleic and linoleic acid.

[0029] Alkyl radicals R¹ and R² which may be mentioned are branched or unbranched C₁-C₁₂-alkyl chains, preferably methyl, ethyl, n-propyl, 1-methylethyl, n-butyl, 1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 2,2-dimethylpropyl, 1-ethylpropyl, n-hexyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl, 1-ethyl-1-methylpropyl, 1-ethyl-2-methylpropyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl.

[0030] Particularly preferred alkyl radicals are C₁-C₆-alkyl chains, in particular methyl, ethyl, n-propyl, 1-methylethyl, n-butyl, 1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 2,2-dimethylpropyl, 1-ethylpropyl, n-hexyl.

[0031] The radicals R¹ and R², together with the oxygen atoms to which they are bonded and the carbon atoms bonded to the oxygen atoms, can form unsubstituted or substituted heterocycles. These are intended to include, for example, cyclic acetals and ketals which, inter alia, are employed as a protective group for the two terminal hydroxyl functions (in the 5- and 6-position) of the acorbic acid. A preferred heterocyclic system is, inter alia, the 5,6-isopropylidene radical, which is formed by reaction of the two free hydroxyl groups in the 5- and 6-position with acetone.

[0032] Suitable alkoxycarbonyl radicals for R¹, R² and R⁴ are those whose alkoxy group contains 1 to 12 C atoms, preferably 1 to 6 C atoms, particularly preferably 1 to 4 C atoms.

[0033] Examples of the preferred radicals which may be mentioned are:

[0034] methoxycarbonyl ethoxycarbonyl

[0035] isopropoxycarbonyl n-propoxycarbonyl

[0036] 1-methylpropoxycarbonyl n-butoxycarbonyl

[0037] n-pentoxycarbonyl 2-methylpropoxycarbonyl

[0038] 3-methylbutoxycarbonyl 1,1-dimethylpropoxycarbonyl

[0039] 2,2-dimethylpropoxycarbonyl hexoxycarbonyl

[0040] 1-methyl-1-ethylpropoxycarbonyl

[0041] Particularly preferred alkoxycarbonyl radicals are:

[0042] methoxycarbonyl ethoxycarbonyl

[0043] sopropoxycarbonyl n-propoxycarbonyl

[0044] 1-methylpropoxycarbonyl n-butoxycarbonyl

[0045] Possible cations for R³ are NH₄ ⁺ and representatives from the group consisting of the alkali and alkaline earth metals, preferably Na, K, Li, Ca and Mg, particularly preferably Na, K and Mg.

[0046] The term ascorbic acid derivatives is understood as meaning both derivatives of L- and D-ascorbic acid (isoascorbic acid), preferably L-ascorbic acid.

[0047] Some di- and tricarbonates of ascorbic acid are already known. Thus U.S. Pat. No. 2,980,702 describes compounds of the 2,5,6-tri-O-(C₁-C₃-alkoxycarbonyl)-L-ascorbic acid type and their use as a heat-resistant additive in foodstuffs, especially in baked goods. JP 42020050 describes the synthesis of 2,6-di-O-(C₁-C₃-alkoxycarbonyl)-L-ascorbic acid as a heat-stable derivative of ascorbic acid.

[0048] The use of the abovementioned ascorbic acid derivatives in cosmetic and pharmaceutical applications, however, is novel.

[0049] The stable ascorbic acid derivatives of the formula I according to the invention are outstandingly suitable as active compounds for cosmetic and pharmaceutical preparations.

[0050] Thus the compounds are distinguished, inter alia, in that, by variation of the radicals R¹, R² and R⁴, the lipophilicity of the ascorbic acid derivatives can be adjusted in a controlled manner. Depending on the demand in the formulation of cosmetic and pharmaceutical preparations, a wide range of stable vitamin C derivatives is thus available to the expert in the field. The tricabonates and the fatty acid esters of vitamin C 2-monocarbonate particularly can be incorporated very readily into preparations such as, for example, ointments, lotions, gels or emulsions on account of their good oil solubility.

[0051] Accordingly, the present invention also relates to cosmetic and pharmaceutical preparations comprising an effective amount of at least one of the compounds of the formula I, and customary cosmetic and pharmaceutical auxiliaries and additives.

[0052] The abovementioned preparations can contain the compounds of the formula I in proportions of from 0.01 to 10% by weight, preferably 0.1 to 8% by weight, particularly preferably 0.5 to 5% by weight, based on the total amount of the cosmetic or pharmaceutical preparation.

[0053] The ascorbic acid derivatives of the formula I can be employed, inter alia, in all cosmetic and pharmaceutical preparations which, in addition to water, also contain emulsifiers, stabilizers, natural oils, cosmetic oils, fats, waxes, silicone oils, silicone oil derivatives, solubilizers, sunscreens, moisturizers, active compounds, consistency-imparting agents, gel-forming agents, antioxidants or preservatives.

[0054] Emulsifiers used are, for example, the following substances:

[0055] Polyglycerol fatty acid esters, ethoxylates of fatty acids, sorbitan fatty acid esters, phosphoric acid esters of fatty acids, phospholipids, glycerol monostearate and self-emulsifying glycerol monostearate.

[0056] Stabilizers are understood as meaning:

[0057] Magnesium and aluminum salts of fatty acids, complexing agents such as EDTA, NTA, MGDA, antioxidants such as BHT, BHA, alpha tocopherol, gallic acid and its salts and esters.

[0058] Natural oils are, for example, jojoba oil, sunflower oil, groundnut oil, almond oil, avocado oil, macadamia nut oil, castor oil, maize germ oil, grapeseed oil.

[0059] Cosmetic oils are, for example, isopropyl esters of fatty acids, very particularly isopropyl stearate, isopropyl palmitate, isopropyl isostearate, isopropyl myristate, isopropyl laurate, paraffin oil, neutral oil.

[0060] Cosmetic active compounds are, for example, panthenol, bisabolol, α-tocopherol, α-tocopheryl acetate, Aloe vera, algal extract, hyaluronic acid, retinol and retinyl esters, phytantriol, panthenyl ethyl ether, ferulic acid.

[0061] Sunscreens which can be used on their own or as a mixture together with the compounds of the formula I are, for example CAS No. No. Substance (= acid)  1 4-Aminobenzoic acid 150-13-0  2 3-(4′-Trimethylammonium)benzylidene- 52793-97-2 bornan-2-one methylsulfate  3 3,3,5-Trimethylcyclohexyl salicylate 118-56-9 (homosalate)  4 2-Hydroxy-4-methoxy-benzophenone 131-57-7 (oxybenzone)  5 2-Phenylbenzimidazole-5-sulfonic acid and its 27503-81-7 potassium, sodium and triethanolamine salts  6 3,3′-(1,4-Phenylenedimethine)bis(7,7-dime- 90457-82-2 thyl-2-oxobicyclo[2.2.1]heptane-1-methane- sulfonic acid) and its salts  7 Polyethoxyethyl 4-bis (polyethoxy)aminobenzoate 113010-52-9  8 2-Ethylhexyl 4-dimethylaminobenzoate 21245-02-3  9 2-Ethylhexyl salicylate 118-60-5 10 2-Isoamyl 4-methoxycinnamate 71617-10-2 11 2-Ethylhexyl 4-methoxycinnamate 5466-77-3 12 2-Hydroxy-4-methoxybenzophenone-5-sulfonic 4065-45-6 acid (sulisobenzane) and the sodium salt 13 3-(4′-Methyl)benzylidenebornan-2-one 36861-47-9 14 3-Benzylidenebornan-2-one 15087-24-8 15 1-(4′-Isopropylphenyl)-3-phenylpropane-1,3- 63250-25-9 dione 16 4-Isopropylbenzyl salicylate 94134-93-7 17 2,4,6-Trianiline-(o-carbo-2′-ethyl- 88122-99-0 hexyl-1′-oxy)-1,3,5-triazine 18 3-Imidazol-4-ylacrylic acid and its ethyl ester 104-98-3 19 Ethyl 2-cyano-3,3-diphenylacrylate 5232-99-5 20 2′-Ethylhexyl 2-cyano-3,3-diphenylacrylate 6197-30-4 21 Methyl o-aminobenzoate or: 134-09-8 5-methyl-2-(1-methylethyl)-2-aminobenzoate 22 Glyceryl p-aminobenzoate or: 136-44-7 1-glyceryl 4-aminobenzoate 23 2,2′-Dihydroxy-4-methoxybenzophenone 131-53-3 (dioxybenzone) 24 2-Hydroxy-4-methoxy-4-methylbenzophenone 1641-17-4 (mexenone) 25 Triethanolamine salicylate 2174-16-5 26 Dimethoxyphenylglyoxalic acid or: 4732-70-01 sodium 3,4-dimethoxyphenylglyoxalate 27 3-(4′-Sulfo)benzylidenebornan-2-one and its 56039-58-8 salts 28 4-tert-Butyl-4′-methoxydibenzoylmethane 70356-09-1 29 2,2′,4,4′-Tetrahydroxybenzophenone 131-55-5

[0062] The ascorbic acid derivatives of the formula I are also suitable for surfactant formulations.

[0063] Thus hair rinses, shampoos, and foams with stable vitamin C of the formula I can be prepared without problems.

[0064] The combination of anionic and cationic surfactants does not restrict use in cosmetic products.

[0065] The invention furthermore relates to ascorbic acid derivatives of the formula Ia,

[0066] where the variables independently of one another have the following meanings:

[0067] R¹ and R² independently of one another

[0068] are hydrogen or C₁-C₂₀-acyl;

[0069] R³ is hydrogen or a cation selected from the group consisting of alkali metals and alkaline earth metals;

[0070] R⁴ is C₁-C₆-alkoxycarbonyl.

[0071] Also claimed are ascorbic acid derivatives of the formula Ib,

[0072] where

[0073] R³ is hydrogen or a cation selected from the group consisting of alkali metals and alkaline earth metals, and

[0074] R⁴ is C₁-C₆-alkoxycarbonyl.

[0075] Acyl radicals for R¹ and R² are understood as meaning branched or unbranched, saturated or unsaturated, if appropriate polyunsaturated, C₁-C₂₀-acyl chains.

[0076] Examples of these are acyl radicals of the formic, acetic, propionic, n-butyric, isobutyric, n-valeric, isovaleric, caproic, caprylic, capric, undecanoic, lauric, tridecanoic, myristic, pentadecanoic, palmitic, palmitoleic, stearic, oleic, linoleic, linolenic, nonadecanoic and arachidonic acid.

[0077] Preferred acyl radicals are those of long-chain fatty acids having C₁₀ to C₂₀ carbon chains, in particular acyl radicals of lauric, palmitic, palmitoleic, stearic, oleic and linoleic acid.

[0078] Suitable alkoxycarbonyl radicals for R⁴ are those whose alkoxy group contains from 1 to 6 C atoms, particularly preferably 1 to 4 C atoms.

[0079] Particularly preferred alkoxycarbonyl radicals are:

[0080] methoxycarbonyl ethoxycarbonyl

[0081] isopropoxycarbonyl n-propoxycarbonyl

[0082] 1-methylpropoxycarbonyl n-butoxycarbonyl

[0083] Possible cations for R³ are representatives of the group consisting of the alkali metals and alkaline earth metals, preferably Na, K, Li, Ca and Mg, particularly preferably Na, K and Mg.

[0084] The synthesis of the ascorbic acid derivatives of the formulae Ia and Ib, starting from the starting materials IIa and IIb, is carried out analogously to the process according to Japanese Patent Publication JP 42020050. Reference is made to this publication with respect to closer details.

[0085] In the following examples, the preparation of the ascorbic acid derivatives of the formula I according to the invention and the composition of cosmetic formulations which contain these ascorbic acid derivatives is illustrated in greater detail.

EXAMPLE 1

[0086] 2,5,6-Tri-O-(isopropyloxycarbonyl)-L-ascorbic acid

[0087] 1.5 l (1.5 mol) of a 1M solution of isopropyl chloroformate in toluene were added dropwise at −15° C. to 80 g (0.454 mol) of L-ascorbic acid in 350 ml (4.3 mol) of pyridine, pyridinium hydrochloride being deposited as a white precipitate. The resulting suspension was stirred at room temperature for a further 1.5 hours and the pyridinium hydrochloride was then filtered off. The yellow filtrate was concentrated in vacuo and the reddish, oily crude product arising therefrom was washed twice with 1M HCl solution after taking up in dichloromethane. The organic lower phase was then extracted four times with saturated (10% strength) sodium hydrogencarbonate solution and the combined aqueous extracts (in each case upper phases) were treated with conc. hydrochloric acid up to the commencement of turbidity (about pH 1). This aqueous suspension was then extracted three times with dichloromethane and the combined organic extracts (in each case lower phases) were dried over Na₂SO₄ and concentrated in vacuo. After vacuum drying, a yellow wax was obtained.

[0088] Yield: 68.0 g (34.5%)

[0089]¹³C-NMR: δ=165.82 (CO-ascorbyl), 154.90 (C-3-ascorbyl), 154.06, 153.58, 153.09 (3× CO-carbonate), 115.04 (C-2-ascorbyl), 76.02 (C-4-ascorbyl), 73.63, 73.25, 73.13 (3× CH(CH₃)₂), 72.88 (C-5-ascorbyl), 64.44 (C-6-ascorbyl), 21.70, 21.69, 21.56, 21.54, 21.48, 21.47 (6× CH₃) ppm.

EXAMPLE 2

[0090]6-O-Palmitoyl-2-O-(isopropyloxycarbonyl)-L-ascorbic acid

[0091] 45 ml (0.045 mol) of a 1M solution of isopropyl chloroformate in toluene were added dropwise at −15° C. to 17.8 g (0.042 mol) of 6-O-palmitoyl-L-ascorbic acid in 100 ml (1.24 mol) of pyridine. The reaction mixture was stirred at room temperature for a further hour and the deposited pyridinium hydrochloride was filtered off. The yellow filtrate was concentrated in vacuo with repeated codistillation with toluene.

[0092] The brown oily residue was taken up in dichloromethane/toluene (1:1) and washed twice with 1M HCl solution. Drying of the organic phase over Na₂SO₄ and concentration in vacuo yielded a dark yellow to brown solid, which, in divided form after suspending twice in a little cold ethyl acetate, was filtered as a white solid.

[0093] Final weight: 13.3 g (61.9%)

[0094]¹³C-NMR: δ=174.11 (CO-palmitoyl), 166.80 (CO-ascorbyl), 156.62 (OCOO-carbonate), 153.23 (C-3-ascorbyl), 114.60 (C-2-ascorbyl), 75.98 (C-4-ascorbyl); 75.60 (OCH(CH₃)₂); 67.94 (C-5-ascorbyl); 64.43 (C-6-ascorbyl); 34.10 (C-2-palmitoyl) ppm.

EXAMPLE 3

[0095]5,6-O-Isopropylidene-2-O-(isopropyloxycarbonyl)-L-ascorbic acid

[0096] 415 ml (0.415 mol) of a 1M solution of isopropyl chloroformate in toluene were added dropwise at −15° C. to 85.3 g (0.395 mol) of 5,6-O-isopropylidene-L-ascorbic acid in 300 ml (3.7 mol) of pyridine, pyridinium hydrochloride being deposited as a white solid. The mixture was stirred at room temperature for a further hour and the pyridinium hydrochloride was then filtered off. The yellow filtrate was concentrated in vacuo with repeated codistillation with toluene. The orange syrup thus obtained was taken up in dichloromethane/toluene (1:1), washed twice with 1M HCl solution and extracted four times in each case with saturated (10% strength) sodium hydrogencarbonate solution. The combined aqueous upper phases were treated with conc. hydrochloric acid until the solution became turbid. The aqueous suspension thus formed was extracted three times with dichloromethane with taking up of the deposited solid. The combined organic extracts were dried over Na₂SO₄ and concentrated in vacuo to obtain a yellow solid.

[0097] Yield: 86 g (72.1%).

[0098] Recrystallization of this colored crude solid from a little warm dichloromethane and suspension of the crystallizate in a little cold ethyl acetate with subsequent filtration yielded a white crystallizate.

[0099] Yield after recrystallization: 47.2 g (39.5%)

[0100]¹³C-NMR: δ=166.21 (CO-ascorbyl), 155.13 (CO-carbonate), 153.46 (C-2-ascorbyl), 114.79 (C-3-ascorbyl), 110.71 (C(CH₃)₂), 76.03 (C-4-ascorbyl), 74.74 (CH(CH₃)₂), 73.52 (C-5-ascorbyl), 65.28 (C-6-ascorbyl), 25.78, 25.55 (C(CH₃)₂), 21.51, 21.50 (CH(CH₃)₂) ppm.

EXAMPLE 4

[0101] 2-O-(Isopropyloxycarbonyl)-L-ascorbic acid

[0102] 47 g (0.155 mol) of 5,6-O-isopropylidene-2-O-(isopropyl-oxycarbonyl)-L-ascorbic acid were stirred for 12 hours at room temperature in 200 ml of a trifluoroacetic acid/water mixture (1:4). The colorless reaction solution was concentrated in vacuo with repeated codistillation. A pale brown syrup (56.4 g, 138.3%) was obtained, which was purified on silica gel (eluent: dichloromethane/methanol 3:1).

[0103] Yield: 43 g (92%)

[0104]¹H-NMR: δ=4.81 (H-4), 4.77 (OCH(CH₃)₂), 3.77 (H-5), 3.49 (2× H-6), 1.30-1.25 (OCH(CH₃)₂) ppm.

[0105] Cosmetic preparations

EXAMPLE 5

[0106] Composition for fat-free sunscreen gel

[0107] Mass content

[0108] (% by weight) 0.40 Acrylate/C₁₀-C₃₀ alkylacrylate crosspolymer 0.25 Hydroxyethylcellulose 8.00 Octyl methoxycinnamate 1.00 4-Methylbenzylidenecamphor 0.50 6-O-Palmitoyl-2-o-(isopropyloxycarbonyl)-L-ascorbic acid 0.20 Disodium EDTA 5.00 Glycerol 0.15 Fragrance 0.30 Imidazolidinyl urea 0.25 Sodium methylparaben 0.15 Sodium propylparaben 5.00 PEG-25 PABA 0.10 Sodium hydroxide to 100 Water

EXAMPLE 6

[0109] Composition for moisturizing cream

[0110] Mass content

[0111] (% by weight) 6.00 PEG-7-hydrogenated castor oil 5.00 Isopropyl palmitate 6.00 Mineral oil 5.00 Jojoba oil 5.00 Almond oil 0.50 Tocopheryl acetate 2.00 6-O-Palmitoyl-2-O-(isopropyloxycarbonyl)-L-ascorbic acid 0.60 Magnesium stearate 2.00 PEG-45/dodecyl glycol copolymer 5.00 Glycerol 0.25 Methylparaben 0.15 Propylparaben 5.00 Imidazolidinylurea 0.15 Fragrance 0.20 Disodium EDTA to 100 Water

EXAMPLE 7

[0112] Composition for moisturizing cream

[0113] Mass content

[0114] (% by weight) 6.00 PEG-7-hydrogenated castor oil 5.00 Isopropyl palmitate 6.00 Mineral oil 5.00 Jojoba oil 5.00 Almond oil 0.50 Tocopheryl acetate 2.00 5,6-O-Isopropylidene-2-O-(isopropyloxycarbonyl)-L-ascorbic acid 0.60 Magnesium stearate 2.00 PEG-45/dodecyl glycol copolymer 5.00 Glycerol 0.25 Methylparaben 0.15 Propylparaben 5.00 Imidazolidinylurea 0.15 Fragrance 0.20 Disodium EDTA to 100 Water

EXAMPLE 8

[0115] Composition for night cream without preservative

[0116] Mass content

[0117] (% by weight) 5.00 PEG-7-hydrogenated castor oil 4.00 Isopropyl palmitate 4.00 Caprylic acid/caprate triglyceride 3.00 6-O-Palmitoyl-2-O-(isopropyloxycarbonyl)-L-ascorbic acid 1.50 PEG-45/dodecyl glycol copolymer 0.50 Magnesium stearate 1.50 Dimethicone 4.00 1,2-Propylene glycol 4.00 Glycerol 8.00 611 alcohol 2.00 Collagen 0.15 Fragrance to 100 Water

EXAMPLE 9

[0118] Composition for antiwrinkle cream

[0119] Mass content

[0120] (% by weight)  6.00 PEG-7-hydrogenated castor oil  5.00 Isopropyl palmitate 10.00 Mineral oil  3.00 Caprylic acid/caprate triglyceride  0.60 Magnesium stearate  1.00 6-O-Palmitoyl-2-O-(isopropyloxycarbonyl)-L-ascorbic acid  1.50 Tocopheryl acetate  2.00 PEG-45/dodecyl glycol copolymer  0.05 Tocopherol  0.20 Retinol  0.30 Glycerol  0.70 Magnesium sulfate  0.25 Methylparaben  0.15 Propylparaben  0.20 Sodium ascorbyl monophosphate  0.10 α-Tocopherol  0.10 Ascorbyl palmitate  0.15 Fragrance to 100 Water

EXAMPLE 10

[0121] Composition for antiwrinkle cream

[0122] Mass content

[0123] (% by weight)  6.00 PEG-7-hydrogenated castor oil  5.00 Isopropyl palmitate 10.00 Mineral oil  3.00 Caprylic acid/caprate triglyceride  0.60 Magnesium stearate  1.00 2,5,6-Tri-O-(isopropyloxycarbonyl)-L-ascorbic acid  1.50 Tocopheryl acetate  2.00 PEG-45/dodecyl glycol copolymer  0.05 Tocopherol  0.20 Retinol  0.30 Glycerol  0.70 Magnesium sulfate  0.25 Methylparaben  0.15 Propylparaben  0.20 Sodium ascorbyl monophosphate  0.10 α-Tocopherol  0.10 Ascorbyl palmitate  0.15 Fragrance to 100 Water

EXAMPLE 11

[0124] Composition for moisturizing day cream

[0125] Mass content

[0126] (% by weight)  2.00 Ceteareth/6  2.00 Ceteareth/25 10.00 Mineral oil  3.00 Caprylic acid/caprate triglyceride  3.00 Isostearic acid  3.00 6-O-Palmitoyl-2-o-(isopropyloxycarbonyl)-L-ascorbic acid  1.50 Tocopheryl acetate  2.00 D-Panthenol USP  0.05 Tocopherol  0.20 Retinol  0.30 Glycerol  0.13 Dibromocyanobutane  0.20 Sodium ascorbyl monophosphate  0.10 α-Tocopherol  0.10 Ascorbyl palmitate  0.15 Fragrance to 100 Water

EXAMPLE 12

[0127] Composition for moisturizing day cream

[0128] Mass content

[0129] (% by weight)  2.00 Ceteareth/6  2.00 Ceteareth/25 10.00 Mineral oil  3.00 Caprylic acid/caprate triglyceride  3.00 Isostearic acid  3.00 2-O-(isopropyloxycarbonyl)-L-ascorbic acid  1.50 Tocopheryl acetate  2.00 D-Panthenol USP  0.05 Tocopherol  0.20 Retinol  0.30 Glycerol  0.15 Dibromocyanobutane  0.20 Sodium ascorbyl monophosphate  0.10 α-Tocopherol  0.10 Ascorbyl palmitate  0.15 Fragrance to 100 Water 

We claim:
 1. The use of ascorbic acid derivatives of the formula I

where the variables independently of one another have the following meanings; R¹ is hydrogen, C₁-C₂₀-acyl, C₁-C₁₂-alkoxycarbonyl, C₁-C₁₂-alkyl; R² is hydrogen, C₁-C₂₀-acyl, C₁-C₁₂-alkoxycarbonyl, C₁-C₁₂-alkyl; where R¹ and R², together with the oxygen atoms to which they are bonded and the carbon atoms bonded to the oxygen atoms, can form an unsubstituted or substituted heterocycle; R³ is hydrogen or a cation selected from the group consisting of NH₄ ⁺, alkali metal and alkaline earth metal cations; R⁴ is C₁-C12-alkoxycarbonyl, for cosmetic and pharmaceutical preparations.
 2. The use of ascorbic acid derivatives as claimed in claim 1, where the variables have the following meanings: R¹ is hydrogen, C₁-C₂₀-acyl, C₁-C₁₂-alkoxycarbonyl, C₁-C₁₂-alkyl; R² is hydrogen, C₁-C₂₀-acyl, C₁-C₁₂-alkoxycarbonyl, C₁-C₁₂-alkyl; where R¹ and R², together with the oxygen atoms to which they are bonded and the carbon atoms bonded to the oxygen atoms, can form an unsubstituted or substituted heterocycle and R¹ must not be a C₁-C₁₂-alkoxycarbonyl radical if R² is hydrogen; R³ is hydrogen or a cation selected from the group consisting of NH₄ ⁺, alkali metal and alkaline earth metal cations; R⁴ is C₁-C₁₂-alkoxycarbonyl.
 3. The use of ascorbic acid derivatives as claimed in claims 1 and 2, where the variables have the following meanings: R¹ is hydrogen, C₁-C₂₀-acyl, C₁-C₆-alkoxycarbonyl; R² is hydrogen, C₁-C₂₀-acyl, C₁-C₆-alkoxycarbonyl;, where R¹ must not be a C₁-C₆-alkoxycarbonyl radical if R² is hydrogen; R³ is hydrogen or a cation selected from the group consisting of NH₄ ⁺, alkali metal and alkaline earth metal cations; R⁴ is C₁-C₆-alkoxycarbonyl.
 4. The use of ascorbic acid derivatives as claimed in claims 1 to 3 as antioxidants in cosmetic and pharmaceutical formulations.
 5. A cosmetic or pharmaceutical preparation comprising an effective amount of at least one of the compounds of the formula I as claimed in claims 1 to 3, and customary cosmetic and pharmaceutical auxiliaries and additives.
 6. An ascorbic acid derivative of the formula Ia,

where the variables independently of one another have the following meanings: R¹ and R² independently of one another are hydrogen or C₁-C₂₀-acyl; R³ is hydrogen or a cation selected from the group consisting of NH₄ ⁺, alkali metal and alkaline earth metal cations; R⁴ is C₁-C₆-alkoxycarbonyl.
 7. An ascorbic acid derivative of the formula Ib,

where R³ is hydrogen or a cation selected from the group consisting of NH₄ ⁺, alkali metal and alkaline earth metal cations, and R⁴ is C₁-C₆-alkoxycarbonyl.
 8. A process for preparing ascorbic acid derivatives of the formula Ia, which comprises reacting an ascorbic acid derivative of the formula IIa

where the substituents R¹ to R³ have the meanings mentioned in claim 6, with an alkyl halocarbonate of chain length C₁ to C₆.
 9. A process for preparing ascorbic acid derivatives of the formula Ib, which comprises reacting an ascorbic acid derivative of the formula IIb

where R³ has the meaning mentioned in claim 7, with an alkyl halocarbonate of chain length C₁ to C₆.
 10. A process for preparing ascorbic acid derivatives as claimed in claims 8 and 9, which comprises using alkyl chloro- or bromocarbonates of chain length C₁ to C₆. 